Development of a PCR-based allele-specific assay from an RFLP probe linked to resistance to cereal cyst nematode in wheat

Mutation and mutation screening

Molecular techniques have created the opportunity for great advances in plant mutation genetics and the science of mutation breeding. The powerful targeted induced local lesions in genomes (TILLING) technique has introduced the possibility of reverse genetics-the ability to screen for mutations at the DNA level prior to assessing phenotype. Fundamental to TILLING is the induction of mutant populations (or alternatively, the identification of mutants in the environment); and mutation induction requires an understanding and assessment of the appropriate mutagen dose required. The techniques of mutation induction, dose optimization, and TILLING are explained.

Developing sustainable systems for nematode management

Early researchers identified key concepts and developed tactics for multiple-option management of nematodes. Although the emphasis on integrated pest management over the past three decades has promoted strategies and tactics for nematode management, comprehensive studies on the related soil biology-ecology are relatively recent. Traditional management tactics include host resistance (where available), cultural tactics such as rotation with nonhosts, sanitation and avoidance, and destruction of residual crop roots, and the judicious use of nematicides. There have been advances in biological control of nematodes, but field-scale exploitation of this tactic remains to be realized. New technologies and resources are currently becoming central to the development of sustainable systems for nematode-pest-crop management: molecular diagnostics for nematode identification, genetic engineering for host resistance, and the elucidation and application of soil biology for general integrated cropping systems. The latter strategy includes the use of nematode-pest antagonistic cover crops, animal wastes, and limited tillage practices that favor growth-promoting rhizobacteria, earthworms, predatory mites, and other beneficial organisms while suppressing parasitic nematodes and other plant pathogens. Certain rhizobacteria may induce systemic host resistance to nematodes and, in some instances, to foliage pathogens. The systems focusing on soil biology hold great promise for sustainable crop-nematode management, but only a few research programs are currently involved in this labor-intensive endeavor.